A generic SCR device is known for example from DE 10 2007 028 480 A1. This known SCR device has a valve arrangement at the upstream end of the liquid conduit, wherein the valve arrangement is designed to close the liquid conduit when a filling level of the reducing liquid in the tank reaches or falls below a minimum filling level.
SCR devices are generally known in order, by injection of a reducing liquid, as a rule aqueous urea solution, into the exhaust gas system of a motor vehicle, to reduce nitrogen oxides present there and thus to decrease the emission of pollutants from the vehicle.